Shopping malls (virtual malls) that allow commercial transactions over the Internet have conventionally been known. A large number of shops (virtual shops) can be set up in such shopping malls. A Web page carrying a list of products being sold by respective shops (a Web page specially created for a campaign for some products, for example) is displayed on a terminal (hereinafter referred to as the “user terminal”) used by a user (a customer) who has accessed a site providing a shopping mall (hereinafter referred to as the “shopping mall site”) over the Internet. When the user selects a product (selects an image of a product, for example) on the Web page displayed on the user terminal, a Web page carrying detailed information about the selected product appears on the user terminal. Such a Web page carrying detailed information about a product is created by the shop that sells the product on the shopping mall site. The page data constituting the created Web page is then uploaded from a terminal used by the shop (hereinafter referred to as the “shop terminal”) into a server managed by the site operator, for example. Patent Document 1 discloses a technique by which a product guide page (a Web page) for introducing products available at a shopping mall site over the internet is created by a shop terminal. Those products are selected from a group of products being actually traded at a real shop. The shop terminal uploads the product guide page to the shopping mall site.